support for making sure exceptions are reset when they should be reset (obs from Nuno Fonseca, #159)

C/c_interface.c

@@ -1939,7 +1939,7 @@ YAP_GoalHasException(Term *t)
 X_API void
 YAP_ClearExceptions(void)
 {
-  Yap_DeleteGlobal(AtomCatch);
+  Yap_ResetExceptionTerm();
   EX = 0L;
   UncaughtThrow = FALSE;
 }